1. Field of the Invention
The invention relates to a device having a tubular sheath associated with a xe2x80x9cdilatorxe2x80x9d tube for putting a catheter tube into place in a vein after the device has been inserted by the xe2x80x9cSeldingerxe2x80x9d method.
2. Background of the Invention
This sildinger method requires the following operations:
1) puncturing the vein with a needle;
2) inserting a metal guide into the vein through the puncturing needle;
3) withdrawing the needle;
4) inserting an assembly constituted by a sheath threaded on a dilator tube over the metal guide;
5) withdrawing the dilator and the guide, leaving the sheath in place;
6) inserting the catheter in the sheath; and
7) withdrawing the sheath.
A problem arises in facilitating insertion of the sheath in the body and extracting it therefrom while reducing the risk of trauma.
Various solutions to that problem are described in the following publications: U.S. Pat. No. 5,499,975, U.S. Pat. No. 5,098,393, WO 99/21605, and EP 0 792 660.
Furthermore, publication FR-A-2 439 591 describes such a tubular sheath (5) which has a resilient slot (6) along its entire length, the distal end (7) thereof being blunted and which is threaded onto a dilator tube (1) whose distal end (3) is tapering.
The term xe2x80x9cresilient slotxe2x80x9d means that the lips of the slot can move apart from each other, but return towards each other when the cause of their moving apart has ceased.
To make it easier to pass through the skin and through the vein wall, the distal ends of the dilator and of the sheath are subjected to treatment:
the dilator tapers so as to obtain a slope whose distal end is as close as possible to the diameter of the guide; and
the sheath is made blunt so as to match the outside diameter of the dilator.
FIG. 1 of the accompanying drawings reproduces FIG. 1 of that publication, the sheath and the dilator being shown separately, while FIG. 2 of the drawings reproduces FIG. 2 of that publication, the sheath being shown threaded on the dilator.
Making the sheath blunt is a difficult operation.
It is necessary to conserve a distal flat (step) to prevent the sheath turning inside-out on passing through tissue.
The sensation of an abutment thus remains as it passes through tissue and the vein, and this gives rise to trauma.
The present invention seeks to remedy those drawbacks.
According to the invention, this is achieved with a device which comprises a sheath having a cylindrical main portion and which is split over its entire length by a resilient slot, said sheath being threaded onto a dilator tube which has a cylindrical main portion and a tapering distal end, and which presents the following features:
the distal end of the tube connects with the main portion of the tube via a shoulder that projects relative to said main portion;
the cylindrical main portion of the sheath terminates at a distal end edge which flares forwardly; and
the shoulder of the tube fits closely to the distal end edge of the sheath.
By means of this combination of characteristics, the tissues are passed through without coming into abutment and thus without trauma.
When the dilator is withdrawn, the slot of the sheath opens to allow the shoulder of the dilator to pass and then returns to its initial (closed) shape after the dilator has been fully withdrawn.